Method of sealing glass and ceramic material together



Jan.6, 1942. E, L6H 2,268,666

METHOD OF SEALING GLASS AND CERAMIC MATERIAL TOGETHER Eiled Jan. 2'7, 1959 which- Patented Jan. 6,1942

METHOD OF SEALING GLASS AND CERAMIC MATERIAL TOGETHER Edmund Lopp, Berlin, Germany, assignor to C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a company Application January 27, 1939, Serial No. 253,165

In Germany January 27,1938

3 Claims.

trontubes and the like it is well known to employ ceramic material. For instance, it is customary to make the wall of such vessels in part of this material.

In this connection dimculties are encountered if glass portions of the vessel are to be sealed to ceramic parts thereof, because thedifierences between the coeflicients of expansion of the respective. parts are such in general that these, when heatedor cooled, willexpand differently, thus causing either the glass or the ceramic material to crack. To employ materials whose coeflicients of expansion are as far as possible similar to .each other is in most cases not suflicient,

as these coeflicients in'their turn depend on temperature conditions in a manner to difier from one another also in this respect.

In accordance with the invention glass and ceramic material are sealed together by uniting the glass with thin-walled parts of the ceramic ;'(O i. 49-81) In the manufacture of vacuum vessels for elecmaterial. In this way, whenever the sealing spot undergoes variations of temperature, there will be a certain freedom of movement provided for the ceramic material which thus will not .be liable to cracking.

Another special advantage is that the respective parts are easy to seal together, since only thin-walled parts, that is, parts of comparatively small volume, are to be heated, whereas the main portion of the' ceramic body will remain almost cold.

In the following description the invention is explained as employed in the manufacture of the vacuum vessel of an electron tube, reference being had to the accompanying drawing, in

Fig. 1 is a fragmentary sectional view of such vessel, while Fig. 2 shows a partial section thereof, taken at right angles to Fig. l. r

The vessel here represented by way of I exam-- ple comprises a ceramic body I, arranged as a cover, and a glass bulb 2. Thes are the parts to be sealed together. 7

In accordance with the invention body I is formed with two thin-walled annular edge portions or projections 3, l which are in the nature of ribs and between which the bulb 2 is inserted. These edge portions may be produced by means of a turning lathe, for instance. In the preferred form shown edge portion 3 is provided with a grooves'between said thin-walled portions and;

tapered cross-section, tapering down longitudimanner to carry electrodes arranged ward in the direction of radii. the ceramic ma- 7 terial or glass bulb thus being prevented from cracking.

Preferably, the ceramic body lwhich'is relatively massive with respect to said annular portions, is made of a porous material so that it will a be intimately united with the glass bulb 2.

In-order to obtain a sealing of this kind, bulb 2 is inserted between the edge portions 3, 4, whereupon these are heated by means of. an acute flame 6 and interconnected thereby in a manner to ensure vacuumtightness.

This mode of sealing provides for heating the 'main portion of body I to such extent only as not to affect the sealing means 8 by which a leading-in conductor 1, for instance, is held in place. This conductor may serve in well-known vacuum vessel.

The invention is not restricted to the manu-.

factureof vacuum vessels for electron tubes, but

may be used whenever glass and ceramic material are to be sealed together.

What is claimed is:

1. A method of sealing a cylindrical glass body to a ceramic cover which comprises forming an- 'nular grooves in said cover, said grooves lying adjacent each other and forming thin-walled inserting one end of said body in one of said sealing said body to said annular. portions.

2. A method of sealing a cylindrical glass body to'a ceramic cover which comprises forming annular grooves in said cover, said grooves lying adjacent each other and forming thin-walled annular portions therebetween, forming radial slots in one of saidthin-walled annular me'mbers, forming at least one of said thin-walled annular portions with a tapered cross-section,

inserting one end of 'said body in'onev ofisaid" V grooves between said thin-walled portions, and

sealing said body to said annular portions.

3. A method ofsealing a cylindrical body to a ceramic cover which comprises forming annular of said thin-walled annular porticns, inserting one end of said body in one of said grooves between. said thin-walled portions and heating said a portions at least to the point at which the glass:

will fuse whereby said body is sealed to said portions.

' Lee? in the r 

